1. Field of the Invention
The present invention relates to a mount inspection apparatus which is used after a BGA mount apparatus for absorbing balls become terminals on a circuit surfaces of BGA (ball grid array) packages so as to mount the balls on the BGA packages. The invention has been developed for the main purpose of providing an apparatus for detecting displacement of solder balls mounted on a plurality of BGA packages provided in a work.
The present application is based on Japanese Patent Application No. Hei. 10-350718, which is incorporated herein by reference.
2. Description of the Related Art
In the related art, in order to detect displacement of solder balls mounted on a work having a plurality of BGA packages, images of alignment marks and images of the solder balls were picked up, and the positions of the solder balls were confirmed with reference to the alignment marks. At that time, the alignment marks and the solder balls were seen in different ways according to a camera. Accordingly, the alignment images and the ball images were picked up while the relative movement between the camera and the BGA packages was stopped at every BGA package. It took much time for inspection because the camera was stopped at every BGA package to pick up images.
It is an object of the present invention to shorten the time of inspection by picking up images of alignment marks of only the top and rearmost ones of BGA packages, making judgement as to whether the positions of mounted balls are good or bad, and inspecting the displacements of the balls, that is, inspecting the number, position, size and so on of solder balls mounted on the BGA packages, without picking up images of alignment marks of BGA packages other than the top and rearmost packages on the basis of initially set BGA package data.
The present invention adopts the following steps in order to solve the foregoing problem. First, assume that, in a ball mount inspection apparatus, a plurality of BGA packages are formed in a work and alignment marks are put at least on the top and rearmost ones of the BGA packages.
Second, the top BGA package is stopped in an image pick-up area, an alignment mark image is picked up, and successively a ball image is picked up while relative movement between the work and a camera is started.
Third, ball images of the second and the following ones of the BGA packages are picked up while the relative movement between the camera and the work is continued, the relative movement is stopped when a ball image of the rearmost BGA package is picked up, and an alignment mark image of the rearmost BGA package is picked up after the relative movement is stopped.
Fourth, the posture of the work as a whole is obtained on the basis of the alignment marks of the top and rearmost BGA packages after the alignment mark image of the rearmost BGA package is picked up, the positions of balls mounted on the BGA packages are calculated while the above-mentioned posture is taken into consideration, and judgment is made as to whether the positions of the mounted balls are good or not.